Thermostats and Operational Methods

ABSTRACT

Thermostats and operational methods are described. According to one aspect, a thermostat includes an interface configured to receive a control signal, wherein the control signal comprises fast components and slow components, and the fast components change at an increased rate compared with slow components of the control signal, control circuitry including a fast response controller configured to use the fast components of the control signal to generate a fast temperature offset, a slow response controller configured to use the slow components of the control signal to generate a slow temperature offset, and wherein the control circuitry is configured to use the fast temperature offset and the slow temperature offset to control a conditioning apparatus to at least one of heat and cool a conditioned area at a plurality of moments in time.

RELATED PATENT DATA

This application claims priority to and the benefit of U.S. ProvisionalPatent Application Serial No. 62/028,736 filed Jul. 24, 2014, titled“Next Generation Transactive Thermostat”, and also claims priority toand the benefit of U.S. Provisional Patent Application Ser. No.62/086,953 filed Dec. 3, 2014, titled “Thermostat for Real-Time PriceDemand Response Using Discrete-Time Control and Zero Deadband”, thedisclosures of which are incorporated herein by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY-SPONSOREDRESEARCH AND DEVELOPMENT

This invention was made with Government support under ContractDE-AC0576RLO1830 awarded by the U.S. Department of Energy. TheGovernment has certain rights in the invention.

TECHNICAL FIELD

This disclosure relates to thermostats and associated operationalmethods.

BACKGROUND OF THE DISCLOSURE

Thermostatically controlled electrical loads can provide valuable energystorage and are prime candidates for fast acting demand response (DR)that can be used to mitigate highly variable renewable power generationand limited availability of ramping resources. However, when someconventional thermostats are retrofitted for real-time price demandresponse control, significant control errors can arise, particularly inthe form of dispatch control drift.

At least some aspects of the disclosure are directed towards thermostatsand associated operational methods which overcome at least some of theshortcomings of conventional thermostats.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the disclosure are described below with referenceto the following accompanying drawings.

FIG. 1 is an illustrative representation of a house according to oneembodiment.

FIG. 2 is a functional block diagram of a thermostat according to oneembodiment.

FIG. 3 is a functional block diagram of a thermostat and house accordingto one embodiment.

DETAILED DESCRIPTION OF THE DISCLOSURE

This disclosure is submitted in furtherance of the constitutionalpurposes of the U.S. Patent Laws “to promote the progress of science anduseful arts” (Article 1, Section 8).

At least some embodiments of the disclosure are directed to thermostatsand associated operational methods which may be used to implement demandresponse control strategies in example implementations. In a morespecific example, the thermostats attempt to distribute electrical loadsevenly throughout the day, and in the presence of peak loads upon theelectrical grid of a utility.

Referring to FIG. 1, example embodiments herein are discussed withrespect to an implementation of a thermostat 12 within a residentialhouse 10. Thermostat 12 controls operational modes of a conditioningapparatus 14, such as a heat pump, to provide either heated or cooledair 18 to heat or cool a conditioned area 15 of house 10. Thermostat 12applies control signals to a controller 16 of conditioning apparatus 14to control the operational modes of the conditioning apparatus 14. Otherthermostatic end-use loads can be controlled using thermostat 12 inother implementations.

In one embodiment, thermostat 12 is used in demand response controlstrategies of electrical utilities as mentioned above. Demand responseis increasingly regarded as an important resource for electricityinterconnections in industrialized economies. Demand response providesboth economic and technical benefits that far outweigh their costs, anddemand response plays an important role in mitigating both the marketpower of electricity suppliers and the intermittency of renewablegeneration. Numerous thermostats 12 may be used in numerous houses 10 toimplement demand response control strategies in but one exampleapplication of use.

Thermostat 12 is transactive and receives a control signal from anexternal source in some of the disclosed embodiments. An electricalutility, or other source, may provide the control signal to thermostats12 implemented with the houses 10 in one embodiment. The control signalis used to implement demand response control strategies in oneembodiment. The control signal may be communicated via any appropriatecommunications method, such via as the Internet, wired, and/or wirelesscommunications and is used by thermostat 12 to control conditioningapparatus 14 as discussed below.

In one embodiment, the control signal is indicative of price ofelectrical energy which is supplied to house 10 and conditioningapparatus 14. The control signal changes as a result of changes in priceof the electrical energy in one embodiment. For example, the controlsignal changes as a result of changes in supply and demand of electricalenergy at different moments in time. The control signal may becalculated from the intersection of supply and demand curves of theelectrical energy in one implementation, and the control signal changesdue to changes in the supply and demand of the electrical energy atdifferent moments in time. In one embodiment, updates to the controlsignal are provided to the thermostat 12 at predefined moments in time,such as every five minutes in one example.

The control signal comprises fast and slow components which correspondto changes of the control signal at different rates. For example, fastcomponents refer to changes of the control signal which are less than anhour and slow components refer to changes of the control signal whichare greater than an hour. In one specific embodiment, the fastcomponents correspond to short term price signals emanating fromdistribution capacity or ancillary service markets and the slowcomponents correspond to long term price signals from bulk energymarkets.

As mentioned above, the control signal is used to implement demandresponse control strategies in one embodiment. Additional detailsregarding demand response, thermostat 12, control signals and otherrelated aspects are discussed in a thesis by Chassin, David P., NewResidential Thermostat for Transactive Systems, University of Victoria,Victoria, BC, December 14, 2014, the teachings of which are incorporatedherein by reference. Furthermore, additional details regarding use ofcontrol signals to control operations of thermostat 12 and conditioningapparatus 14 are discussed below with respect to FIG. 3.

Referring to FIG. 2, one embodiment of circuitry of thermostat 12 isshown. In the illustrated example embodiment, thermostat 12 includes auser interface 20, a temperature sensor 22, processing circuitry 24,storage circuitry 26, and communications circuitry 28. Other embodimentsare possible including more, less and/or alternative components.

User interface 20 is configured to interact with a user includingconveying data to a user (e.g., current temperature, temperature setpoints, operational mode, program cycles for wake/sleep/away/home) aswell as receiving inputs from the user, for example, selecting theoperational modes, such as heat, cool, and off.

In one embodiment, processing circuitry 24 is arranged to process data,control data access and storage, issue commands, and control otherdesired operations. In one more specific embodiment, processingcircuitry 24 is configured to perform the operations of the thermostatcontroller and state estimator discussed below with respect to FIG. 3.

Processing circuitry 24 comprises circuitry configured to implementdesired programming provided by appropriate computer-readable storagemedia in at least one embodiment. For example, the processing circuitry24 may be implemented as one or more processor(s) and/or other structureconfigured to execute executable instructions including, for example,software and/or firmware instructions. Other example embodiments ofprocessing circuitry 24 include hardware logic, PGA, FPGA, ASIC, statemachines, and/or other structures alone or in combination with one ormore processor(s). These examples of processing circuitry 24 are forillustration and other configurations are possible. Processing circuitry24 may also be referred to as control circuitry which is configured toimplement operations of thermostat 12 discussed below with respect toFIG. 3.

Storage circuitry 26 is configured to store programming such asexecutable code or instructions (e.g., software and/or firmware),electronic data, databases, image data, or other digital information andmay include computer-readable storage media. At least some embodimentsor aspects described herein may be implemented using programming storedwithin one or more computer-readable storage medium of storage circuitry26 and configured to control appropriate processing circuitry 14.

The computer-readable storage medium may be embodied in one or morearticles of manufacture which can contain, store, or maintainprogramming, data and/or digital information for use by or in connectionwith an instruction execution system including processing circuitry 24in one embodiment. For example, computer-readable storage media may benon-transitory and include any one of physical media such as electronic,magnetic, optical, electromagnetic, infrared or semiconductor media.Some more specific examples of computer-readable storage media include,but are not limited to, a portable magnetic computer diskette, such as afloppy diskette, a zip disk, a hard drive, random access memory, readonly memory, flash memory, cache memory, and/or other configurationscapable of storing programming, data, or other digital information.

Communications circuitry 28 is arranged to implement communications ofthermostat 12 with respect to external devices and/or networks (notshown). For example, communications interface 28 may be arranged tocommunicate information bi-directionally with respect to thermostat 12.Communications interface 28 may be implemented as a network interfacecard (NIC), serial or parallel connection, USB port, Firewire interface,Ethernet port, flash memory interface, or any other suitable arrangementfor implementing communications of thermostat 12. In one embodiment,communications circuitry 28 outputs control signals which control theoperational modes of conditioning apparatus 14. In addition,communications circuitry 28 may receive control signals, from externalof the thermostat 12, and which may include control signals which areindicative of the price of electrical energy supplied to house 10 in atleast one embodiment.

Referring to FIG. 3, operations of one embodiment of thermostat 12 aredescribed. Thermostat 12 includes plural subsystems including athermostat controller 30 and a state estimator 32 in the depictedexample embodiment. The thermostat controller 30 is configured tocontrol operations of conditioning apparatus 14 to at least one of heatand cool a conditioned area 15 of house 10. State estimator 32 isconfigured to provide information regarding a mass temperature of theconditioned area 15.

In one embodiment, the thermostat controller 30 and state estimator 32are discrete-time control subsystems which are implemented usingprocessing circuitry 24 described above. Processing circuitry 24implementing the operations of thermostat controller 30 and stateestimator 32 may also be referred to as control circuitry.

Thermostat controller 30 operates to implement changes to theoperational mode of conditioning apparatus 14 at a plurality of discretemoments in time which are predefined according to a discrete, finiteinterval or period in one embodiment. The state estimator 32 operates tosample the data from the house 10 (e.g., the operational mode M of theconditioning apparatus and the air temperature T_(A)) and provide datawhich is indicative of the mass temperature of the conditioned area 15to controller 30 at discrete moments in time defined according to acommon interval or period in one embodiment.

The sampling frequency of the state estimator 32 is faster than thefrequency used by thermostat controller 30 to make changes to theoperational mode of conditioning apparatus 14 in one embodiment. Forexample, the state estimator 32 may operate at a frequency which is 10times faster than the operational frequency of the thermostat controller30 (e.g., the sampling rate of state estimator 32 may be i_(s)=30seconds while thermostat controller 30 operates to access updates to thecontrol signal and change the operational mode of conditioning apparatus14 at a rate i_(s)=5 minutes in one embodiment).

Thermostat controller 30 receives a control signal P_(c) via aninterface 34 of communications circuitry 28, for example, from a utilitywhich supplies electrical energy to house 10 or other appropriatesource. The source of the control signal provides changes or updates tothe control signal at discrete moments in time, such as every fiveminutes, in one embodiment. In one more specific embodiment, thermostatcontroller 30 makes changes to the operational mode of the conditioningapparatus 14 at discrete moments in time which are synchronized with theupdates to the control signal.

In addition to the control signal, thermostat controller 30 alsoreceives a desired temperature set point T_(D) of conditioned area 15,for example, via user interface 20 as set by the occupant of the house10.

In one embodiment, the control signal is filtered to separate the signalinto components with time-constants that correspond to the building massresponse of the conditioned area of the house (long or slow-termresponse) and components with time-constants that correspond to theair's response of the conditioned area of the house (short or fast-termresponse), denoted as slow response and fast response components,respectively. The fast components change at an increased rate comparedwith the slow components. In one embodiment, the thermostat controller30 controls the long-term response of the house using the slowcomponents independently of control of the short-term response of thehouse using the fast components.

The control signal P_(c) received by the thermostat 12 is provided to afast response controller 36 and a slow response controller 38 in theillustrated embodiment. Fast and slow response controllers 36, 38 areconfigured to relate or convert changes in price information to changesin temperature in one embodiment. For example, fast and slow responsecontrollers 36, 38 process respective fast and slow components of thecontrol signal to generate to respective fast and slow temperatureoffsets in one embodiment. The fast and slow temperature offsets areused to adjust the desired temperature set point selected by the userbased upon the control signal, which may include price information asset forth in the following continuing discussion.

One embodiment of fast controller 36 calculates a fast temperatureoffset T_(F) according to the following:

$\begin{matrix}{T_{F} = \frac{{F_{H}\left( P_{C} \right)} - P_{A}}{K}} & (1)\end{matrix}$

where P_(A) is the expected price of electricity (e.g., an average priceof electrical energy supplied to the house over the previous 24 hours),P_(C) is the most recently-received price of the electrical energy,F_(H) is a high-pass filter with a cut-off frequency corresponding toapproximately 1 hour (i.e., about 3600⁻¹ Hz) to pass only fastcomponents and filter the slow components of the control signal, and ademand response control gain or comfort gain K=P_(D)/delta T_(m) whereP_(D) is the standard deviation of the price of the electrical energyand delta T_(m) is the occupant's maximum allowed temperature deviationfrom the desired temperature set point (e.g., 2° F.). Delta T_(m) mayalso be equal to k/(T_(m)−T_(D)) where k is a comfort setting which isselected by the occupant and which is indicative of a customerpreference of comfort with respect to temperature (e.g., from 0 formaximum comfort to >100 for maximum savings in one embodiment), T_(D) isthe desired air temperature set point of the conditioned area of thehouse selected by the occupant, and T_(m) is the minimum or maximumallowed air indoor temperature, which is selected based upon whether theair temperature of the conditioned area of the house is above or belowthe desired temperature set point. When the indoor air temperature ofthe house is below the desired temperature set point, the minimumallowed indoor air temperature is used for T_(m), and when the indoorair temperature of the house is above the desired temperature set point,the maximum allowed indoor air temperature is used for T_(m).

One embodiment of the slow response controller 38 operates similarly tothe fast response controller 36 but a low-pass filter F_(L) is utilizedinstead of F_(H) to calculate a slow temperature offset T_(s). Thelow-pass filter has the same cut-off frequency as the fast responsecontroller 36 but only passes slow components with frequencies lowerthan about 3600⁻¹ Hz and filters the fast components in the describedembodiment.

One embodiment of slow controller 38 calculates a slow temperatureoffset T_(s) according to the following:

$\begin{matrix}{T_{S} = \frac{{F_{L}\left( P_{C} \right)} - P_{A}}{K}} & (2)\end{matrix}$

State estimator subsystem 32 is configured to use the operational mode(M) of the conditioning apparatus 14 and the indoor air temperature ofthe conditioned area of the house T_(A), which may be measured, toestimate the mass temperature T_(M) of the conditioned area 15 of thehouse 10. A simple observer/state estimator 33 of subsystem 32 may beimplemented using standard control theory in one embodiment since thetransfer function between air temperature and mass temperature is afirst-order system. Additional details regarding one implementation ofstate estimator subsystem 32 are discussed in Shengwei Wang and XinhuaXu, “Parameter Estimation of Internal Thermal Mass of Building DynamicModels using Genetic Algorithm”, Energy Conversion and Management 47,2005, pages 1927-1941, the teachings of which are incorporated herein byreference.

House 10 is a continuous subsystem and plural analog-to-digitalconverters 40, 42 provide digitized data of the mode of conditioningapparatus 14 and the measured indoor air temperature of the conditionedarea 15 of the house 10 for use in the discrete state estimatorsubsystem 32 in the illustrated embodiment. The output of stateestimator subsystem 32 is indicative of the mass temperature T_(M) ofthe house 10 and is applied to an analog-to-digital converter 46 whichprovides digitized data of the mass temperature T_(M) for use within thethermostat controller subsystem 30. In one embodiment, the differentvalues of the mass temperature T_(M) are provided at a rate i_(s)=30seconds.

The control circuitry of the thermostat 12 implementing the thermostatcontroller subsystem 30 is configured to use the fast and slowtemperature offsets to control operation of conditioning apparatus 14 toheat and cool the conditioned area 15 of the house 15 at differentdiscrete moments in time. In one more specific embodiment, thermostatcontroller 30 is configured to determine a difference 48 between theslow temperature offset T_(s) and mass temperature T_(M). The determineddifference is added 50 to the fast temperature offset T_(F) to provide acombined temperature offset which is added 52 to the desired temperatureset point T_(D) of conditioned area 15 to provide an adjustedtemperature set point T_(C). The adjusted temperature set point T_(c)implements demand response control operations and is the new temperatureset point which is desired to be controlled to in consideration of theprice of the electrical energy which is supplied to the house 10 in thedescribed embodiment.

An error E corresponding to the difference between the adjustedtemperature set point T_(c) and the measured air temperature T_(A) ofthe conditioned area 15 is applied to mode controller 56 which uses thedetermined error to control the operational mode of conditioningapparatus 14.

In one embodiment, mode controller 56 may have two set points, one forheating and one for cooling. The mode controller 56 may also operate inan automatic mode to automatically choose heating or cooling based onthe temperature set points in at least one embodiment. In anotherembodiment, the user selects heating or cooling and the mode controller56 controls whether the conditioning apparatus 14 is on or off atdifferent moments in time. In addition, the mode controller 56 maysupport occupancy schedules to allow occupants to assign different setpoints for specific hours of the day and days of the week.

If the error E which is applied to mode controller 56 is negative, theair temperature T_(A) is greater than expected and mode controller 56outputs a mode control signal M which is equal to −1 to instruct theconditioning apparatus 14 to be in the “on” operational mode to cool theconditioned area 15. If the error E is zero, the air temperature T_(A)is at the expected temperature and mode controller 56 outputs a modecontrol signal M which is equal to 0 to instruct the conditioningapparatus 14 to be in the “off” operational mode to cool the conditionedarea 15. If the error E is positive, the air temperature T_(A) is lessthan expected and mode controller 56 outputs a mode control signal Mwhich is equal to 1 to instruct the conditioning apparatus 14 to be inthe “on” operational mode to heat the conditioned area 15. In someembodiments, the mode controller outputs a mode control signal M whichis equal to 2 to instruct the conditioning apparatus 14 to be in thesupplemental or emergency heating mode.

As mentioned above, the error E is used to change the operational modeof the conditioning apparatus 14 at discrete moments in time, forexample, according to a common interval or period, such as every 5minutes in the described embodiment. In addition, the operational modeselected by the mode controller 56 at the beginning of a given intervalis maintained for the entire interval in one embodiment. Thiscontrolling the change of operational mode at such discrete moments intime and maintaining the same operational mode during the entireinterval prevents quick cycling of the conditioning apparatus 14 betweendifferent operational modes.

In particular, in one embodiment, the length of time of the interval orperiod between the discrete moments in time when changes to theoperational mode are allowed be made may be greater than a minimumruntime of the conditioning apparatus (e.g., air conditioners andheat-pumps may have minimum runtime requirements to allow for pressureequalization before the next start to reduce motor wear and tear thatoccurs during compressor start-up with non-zero vapor back-pressure).The selection of the length of the interval to be greater than theminimum runtime of the conditioning apparatus 14 in combination with themaintenance of the conditioning apparatus in the same operational modeduring the length of the entire interval according to one embodimentassures that the conditioning apparatus 14 is operated appropriately anddoes not cycle too quickly.

In addition, this discrete control by thermostat controller 30 accordingto one embodiment enables control of the operational mode of theconditioning apparatus 14 with zero deadband and changes to theoperational mode of the conditioning apparatus 14 may be made withouthysteresis. For example, some conventional analog and digitalthermostats change the operational mode after the actual temperature ofa conditioned area exceeds a set point by an amount which equal to thedeadband to reduce quick cycling. However, in the presently-describedembodiment, changes are made to the operational mode by the thermostatcontroller 30 at defined moments in time based upon adjusted temperatureset point T_(C) and the measured air temperature T_(A) and not due tochanges in temperature in excess of a deadband.

In one embodiment, changes to the operational mode of the conditioningapparatus (e.g., every 5 minutes) are synchronized in time with thereception of updates to the control signal (e.g., every 5 minutes).Furthermore, although changes to the operational mode of theconditioning apparatus 14 are made at discrete moments in time definedby an interval, the operational mode may remain the same before andafter individual discrete moments in time without a change if the errordoes not indicate that changes to the operational mode should be made.

The output of mode controller 56 is applied to digital-to-analogconverter 58 and the digitized output M controls the operational mode ofconditioning apparatus 14. The converter 58 operates as a zero ordersample/hold circuit in the illustrated embodiment which holds a constantoutput for the duration of an interval and which makes the discreteinput from the mode controller 56 at the beginning of an interval appearas a continuous signal throughout the respective interval.

The control signal M is applied to the conditioning apparatus 14 tocontrol the operational mode of conditioning apparatus 14 to heat orcool the conditioned area 15. Element G of FIG. 3 corresponds to thecoil, compressor and fan of conditioning apparatus 14 and the amount ofpower (W) and energy (W_(h)) to generate the heat Q which is applied tothe conditioned area 15 may also be determined and output.

As discussed herein, some embodiments of the thermostat have minimal orzero deadband (hysteresis) which reduces aggregate load drift (reducesdifferences between measured load and cleared load) while maintainingsatisfactory control of temperature of the conditioned area.Furthermore, consumers may configure the thermostat with differentcomfort preferences for different occupancy modes such as home, away,wake, sleep, etc. in one implementation. The disclosed thermostatsprovide energy shifting (reduce or increase in load) and cost savingsbased upon the control signal and provide an energy demand elasticity ofan entire residential load between 10%-25% for air conditioning (heatingor cooling) during peak times in some embodiments. Further elasticity isprovided if the thermostats are used with other thermostatic end-useloads, such as refrigerators, freezers, water heaters, dish washers,clothes washers, and dryers.

Furthermore, at least some embodiments of the thermostats provide demandresponse in real-time distribution capacity auction systems. Thedisclosed thermostats may be implemented in arrangements to providedemand response which is one of the most cost-effective intermittencymitigation resources available to grid operators. At least someembodiments of the thermostat provide benefits of transactive systems,which implement demand response based on price of electricity (or othercontrol), including environmental benefits associated with increasedintegration of renewable resources.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended aspectsappropriately interpreted in accordance with the doctrine ofequivalents.

Further, aspects herein have been presented for guidance in constructionand/or operation of illustrative embodiments of the disclosure.Applicant(s) hereof consider these described illustrative embodiments toalso include, disclose and describe further inventive aspects inaddition to those explicitly disclosed. For example, the additionalinventive aspects may include less, more and/or alternative featuresthan those described in the illustrative embodiments. In more specificexamples, Applicants consider the disclosure to include, disclose anddescribe methods which include less, more and/or alternative steps thanthose methods explicitly disclosed as well as apparatus which includesless, more and/or alternative structure than the explicitly disclosedstructure.

What is claimed is:
 1. A thermostat comprising: an interface configuredto receive a control signal, wherein the control signal comprises fastcomponents and slow components, and the fast components change at anincreased rate compared with the slow components of the control signal;control circuitry comprising: a fast response controller configured touse the fast components of the control signal to generate a fasttemperature offset; a slow response controller configured to use theslow components of the control signal to generate a slow temperatureoffset; and wherein the control circuitry is configured to use the fasttemperature offset and the slow temperature offset to control aconditioning apparatus to at least one of heat and cool a conditionedarea at a plurality of moments in time.
 2. The thermostat of claim 1wherein the fast response controller is configured to filter the slowcomponents of the control signal and the slow response controller isconfigured to filter the fast components of the control signal.
 3. Thethermostat of claim 1 wherein the control circuitry is configured to usea comfort setting of a customer which is indicative of a customerpreference of comfort with respect to temperature to generate the fastand slow temperature offsets.
 4. The thermostat of claim 1 wherein thecontrol circuitry is configured to use a mass temperature of theconditioned area, a desired temperature set point of the conditionedarea, and an air temperature of the conditioned area to control theoperation of the conditioning apparatus to at least one of heat and coolthe conditioned area.
 5. The thermostat of claim 4 wherein the controlcircuitry is configured to: determine a first difference between theslow temperature offset and a mass temperature of the conditioned area;add the first difference to the fast temperature offset to provide acombined temperature offset; add the combined temperature offset to thedesired temperature set point of the conditioned area to provide anadjusted temperature set point; determine a second difference betweenthe adjusted temperature set point and the air temperature of theconditioned area; and use the second difference to control theconditioning apparatus.
 6. The thermostat of claim 1 wherein the controlsignal is indicative of price of electrical energy which is supplied tothe conditioning apparatus.
 7. The thermostat of claim 6 wherein thecontrol signal changes as a result of changes in the price of electricalenergy which is supplied to the conditioning apparatus.
 8. Thethermostat of claim 1 wherein the control circuitry is configured tocontrol operation of the conditioning apparatus in different operationalmodes at different discrete moments in time to at least one of heat andcool the conditioned area.
 9. The thermostat of claim 8 wherein thecontrol circuitry is configured to use the fast and slow temperatureoffsets to determine that a change of the conditioning apparatus from afirst operational mode to a second operational mode is appropriate, andto control the conditioning apparatus to change from the firstoperational mode to the second operational mode with zero deadband andwithout hysteresis.
 10. The thermostat of claim 1 wherein the controlcircuity comprises discrete control circuitry configured to change anoperational mode of the conditioning apparatus only at a plurality ofdiscrete moments in time.
 11. The thermostat of claim 10 wherein thecontrol circuity is configured to change the operational mode at thediscrete moments in time which are defined by an interval.
 12. Thethermostat of claim 11 wherein the control circuitry is configured tomaintain the conditioning apparatus in the same operational mode for anentirety of the interval.
 13. The thermostat of claim 11 wherein thediscrete moments in time correspond to updates in the price signal atdifferent moments in time.
 14. The thermostat of claim 11 wherein themass temperature information is generated by a state estimator whichsamples the air temperature of the conditioned area at an increased ratecompared with the rate of the discrete moments in time defined by theinterval.
 15. The thermostat of claim 11 wherein the interval is greaterthan a minimum runtime of the conditioning apparatus.
 16. The thermostatof claim 1 wherein the fast and slow response controllers are configuredto use a maximum allowed temperature deviation from a desiredtemperature set point of the conditioned area to generate the fast andslow temperature offsets.